39 research outputs found
Extended state floating up in a lattice model: Bona fide levitation fingerprints, irrespective of the correlation length
The evolution of extended states with magnetic field and disorder intensities
is investigated for 2D lattice models. The floating-up picture is revealed when
the shift of the extended state, relative to the density of states, is properly
taken into account, either for white-noise or correlated disorder.Comment: 4 pages, 4 figures. EP2DS-14 Pragu
Electrostatic theory for imaging experiments on local charges in quantum Hall systems
We use a simple electrostatic treatment to model recent experiments on
quantum Hall systems, in which charging of localised states by addition of
integer or fractionally-charged quasiparticles is observed. Treating the
localised state as a compressible quantum dot or antidot embedded in an
incompressible background, we calculate the electrostatic potential in its
vicinity as a function of its charge, and the chemical potential values at
which its charge changes. The results offer a quantitative framework for
analysis of the observations.Comment: 4 pages, 3 figure
Quantifying the levitation picture of extended states in lattice models
The behavior of extended states is quantitatively analyzed for two
dimensional lattice models. A levitation picture is established for both
white-noise and correlated disorder potentials. In a continuum limit window of
the lattice models we find simple quantitative expressions for the extended
states levitation, suggesting an underlying universal behavior. On the other
hand, these results point out that the Quantum Hall phase diagrams may be
disorder dependent.Comment: 5 pages, submitted to PR
Estudo histológico e histoquímico da pele de jurará Kinosternon scorpioides scorpioides (Testudines: Kinosternidae)
Atmosfera modificada e condições de armazenamento nas características físico-químicas de jabuticabas da cultivar 'paulista'
Exigência de energia de mantença e composição corporal e do ganho de vacas de corte adultas de três grupos genéticos confinadas
Diferentes níveis protéicos na dieta de girinos de rã-touro (Lithobates catesbeianus) e seus efeitos sobre o tecido hepático
Social cognition impairment in genetic frontotemporal dementia within the GENFI cohort
A key symptom of frontotemporal dementia (FTD) is difficulty interacting socially with others. Social cognition problems in FTD include impaired emotion processing and theory of mind difficulties, and whilst these have been studied extensively in sporadic FTD, few studies have investigated them in familial FTD. Facial Emotion Recognition (FER) and Faux Pas (FP) recognition tests were used to study social cognition within the Genetic Frontotemporal Dementia Initiative (GENFI), a large familial FTD cohort of C9orf72, GRN, and MAPT mutation carriers. 627 participants undertook at least one of the tasks, and were separated into mutation-negative healthy controls, presymptomatic mutation carriers (split into early and late groups) and symptomatic mutation carriers. Groups were compared using a linear regression model with bootstrapping, adjusting for age, sex, education, and for the FP recognition test, language. Neural correlates of social cognition deficits were explored using a voxel-based morphometry (VBM) study. All three of the symptomatic genetic groups were impaired on both tasks with no significant difference between them. However, prior to onset, only the late presymptomatic C9orf72 mutation carriers on the FER test were impaired compared to the control group, with a subanalysis showing differences particularly in fear and sadness. The VBM analysis revealed that impaired social cognition was mainly associated with a left hemisphere predominant network of regions involving particularly the striatum, orbitofrontal cortex and insula, and to a lesser extent the inferomedial temporal lobe and other areas of the frontal lobe. In conclusion, theory of mind and emotion processing abilities are impaired in familial FTD, with early changes occurring prior to symptom onset in C9orf72 presymptomatic mutation carriers. Future work should investigate how performance changes over time, in order to gain a clearer insight into social cognitive impairment over the course of the disease